Assume that an investor sells an S&P 500 stock-index futures contract at 975 and buys this contract after a fe

A. -$5000
B. -$1000
C. -$2500
D. -$10

Please help!
Complete Question:

Assume that an investor sells an S&P 500 stock-index futures contract at 975 and buys this contract after a few weeks for 985. The dollar return on this transaction will amount to which of the above?

Please help!

<<<C. -$2500>>>

The future is 250 times the index.